Live Translator

Real-time captions and translation for any video. Works with a local companion app for private speech-to-text.

Live Translator is a browser extension that provides real-time audio transcription and translation with close-captioning on videos. ### Features Audio Capture & Transcription - Captures audio from browser tabs using the Tab Capture API (Chrome) or HTML5 captureStream() (Firefox) - Streams audio to a local companion app (whisper.cpp) for real-time speech-to-text processing - All processing runs locally on your machine — nothing is sent to external servers Translation - Translates transcribed speech into a user-selected target language - Supports multiple translation models via the companion app - Source language can be set manually or left on auto-detect Caption Overlays - Injects a close-captioning overlay at the bottom of HTML5 video elements - Shows original text and translated text simultaneously - Adjustable opacity (background darkness) and font size - Captions auto-hide after 5 seconds of silence - Fade-in animation for smooth appearance Video Player Integration - Injects a "Caption" button directly onto video players (YouTube, Twitch, etc.) - Button appears on hover — toggle captions with one click - Automatically detects video elements even on dynamic/SPA websites - Re-checks periodically for late-loading videos Model Management (Popup) - Browse, download, select, and delete STT models - Visual indicators for active, downloaded, and available models - Model size and translation capability shown in the list - One-click model switching Companion App Integration - WebSocket connection to ws://127.0.0.1:9876 - Auto-reconnect with configurable delay - Status indicators (connecting, connected, error) - Download link for the companion app when not detected Settings & Preferences - Server address configuration - Source and target language selection - Caption mode (video overlay only in this release) - Opacity and font size controls - All settings persisted via storage.local ### Technical Chrome MV3 with service worker Firefox MV2 with non-persistent background page PCM audio streaming (Int16, 16kHz sample rate) WebSocket binary protocol for audio data All innerHTML usage replaced with safe DOM methods for store compliance